Investment Securities (Credit Losses on Impaired Securities) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
OTTI credit losses on previously impaired securities	$ 25	$ 200	$ 29	$ 581
Securities Available for Sale
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Beginning balance	1,867	1,613	1,863	1,232
OTTI credit losses on previously impaired securities	25	200	29	581
Ending balance	$ 1,892	$ 1,813	$ 1,892	$ 1,813